U.S. patent number 5,301,355 [Application Number 07/551,355] was granted by the patent office on 1994-04-05 for modulated signal transmitting apparatus.
This patent grant is currently assigned to Pioneer Electronic Corporation. Invention is credited to Hiroshi Koinuma, Hiroshi Terashima.
United States Patent |
5,301,355 |
Koinuma , et al. |
April 5, 1994 |
Modulated signal transmitting apparatus
Abstract
An infrared remote control signal is entered into a receiving
circuit where it is converted into an electrical, modulated signal
made up of a carrier and a command signal. The modulated input
signal is sent to a control signal output circuit where it is
filtered to send only the carrier of the remote input signal to a
frequency-voltage conversion circuit. The frequency-voltage
conversion circuit generates a control DC voltage according to the
carrier frequency. The control DC voltage changes the pass band
characteristic of a voltage-controlled filter in such a manner that
the voltage-controlled filter selectively passes the desired
fundamental frequency component and harmonic components of the
carrier signal. The voltage-controlled filter also passes the
command signal component. Thus, at the output of the
voltage-controlled filter is obtained a modulated output signal
whose carrier frequency is varied from that of the modulated input
signal. With the carrier frequency changed, the resulting infrared
remote control signal sent out from a transmitting circuit can be
prevented from being affected or interfered with by external noise
from fluorescent lamps.
Inventors: |
Koinuma; Hiroshi (Tokyo,
JP), Terashima; Hiroshi (Tokyo, JP) |
Assignee: |
Pioneer Electronic Corporation
(Tokyo, JP)
|
Family
ID: |
13769073 |
Appl.
No.: |
07/551,355 |
Filed: |
July 12, 1990 |
Foreign Application Priority Data
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Jul 14, 1989 [JP] |
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1-82246[U] |
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Current U.S.
Class: |
455/21; 398/126;
398/176; 455/114.2; 455/306 |
Current CPC
Class: |
H04B
10/11 (20130101) |
Current International
Class: |
H04B
10/10 (20060101); H04B 007/15 () |
Field of
Search: |
;455/20,21,84,114,118,119,120,63,68,67,340,307,266,23,85,87,22,306,921,352
;359/174,142,143,144,145,146,147,148 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1909678 |
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Feb 1969 |
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DE |
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0316030 |
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Dec 1989 |
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JP |
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0718888 |
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Feb 1980 |
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SU |
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Primary Examiner: Eisenzopf; Reinhard J.
Assistant Examiner: Pham; Chi
Attorney, Agent or Firm: Sughrue, Mion, Zinn, Macpeak &
Seas
Claims
What is claimed is:
1. A modulated signal receiving and transmitting apparatus
comprising:
a receiving circuit for receiving from a distant transmitter a
first modulated signal modulated by a first control signal;
a filter coupled to said receiving circuit for passing only a
carrier signal of said first modulated signal;
a frequency-voltage conversion circuit coupled to said filter for
outputting a DC voltage corresponding to a frequency of the carrier
signal from the filter;
a voltage-controlled filter for receiving said first modulated
signal from said receiving circuit and for outputting a second
modulated signal, said voltage-controlled filter having a pass band
characteristics which is changed according to said DC voltage so
that at least a fundamental component of said carrier signal of the
first modulated signal can be passed therethrough; and
a transmitting circuit for transmitting said second modulated
signal to a controlled apparatus.
2. The modulated signal receiving and transmitting apparatus as
claimed in claim 1, wherein said voltage-controlled filter passes a
command signal component of said carrier signal of said first
modulated signal therethrough, and prevents a fundamental component
and harmonic components of said carrier signal of said first
modulated signal which are affected by external noise from passing
therethrough.
3. The modulated signal receiving and transmitting apparatus as
claimed in claim 1, wherein said voltage-controlled filter
comprises:
voltage-controlled oscillation circuit for producing a new carrier
signal at an oscillation frequency determined according to said DC
voltage from said frequency-voltage conversion circuit;
a demodulating circuit for demodulating said first modulated signal
from said receiving circuit and for outputting a command signal
included in said first control signal; and
a modulating circuit for modulating said new carrier signal from
said voltage-controlled oscillation circuit with said command
signal as an output signal of said demodulating circuit to output a
second modulated signal.
4. The modulated signal receiving and transmitting apparatus as
claimed in claim 1, wherein said first modulated signal inputted to
said receiving circuit and said second modulated signal outputted
from said transmitting circuit are infrared signals.
5. The modulated signal receiving and transmitting apparatus as
claimed in claim 1, wherein said first modulated signal inputted to
said receiving circuit is transmitted from a remote controller in a
room different from one in which said transmitting circuit is
installed.
6. The modulated signal receiving and transmitting apparatus as
claimed in claim 1, wherein said first modulated signal inputted to
said receiving circuit is outputted from a transmitter through a
wire, and said second signal modulated signal outputted from said
transmitting circuit is transmitted through a wire.
7. A modulated signal receiving and transmitting apparatus
comprising:
a receiving circuit for receiving from a distant transmitter a
first modulated signal modulated by a first control signal;
a filter coupled to said receiving circuit for passing only a
carrier signal of said first modulated signal;
a frequency-voltage conversion circuit for outputting a DC voltage
corresponding to a frequency of the carrier signal from the
filter;
a voltage-controlled oscillation circuit for producing a new
carrier signal having an oscillation frequency determined according
to said DC voltage from the frequency-voltage conversion
circuit;
a demodulating circuit for demodulating said first modulated signal
from said receiving circuit and for outputting a command signal
included in said first control signal;
a modulating circuit for modulating said new carrier signal from
said voltage-controlled oscillation circuit with said command
signal as an output signal of said demodulating circuit to output a
second modulated signal; and
a transmitting circuit for transmitting said second modulated
signal.
8. The modulated signal receiving and transmitting apparatus as
claimed in claim 7, wherein said first modulated signal inputted to
said receiving circuit and said second modulated signal outputted
from said transmitting circuit are infrared signals.
9. The modulated signal receiving and transmitting apparatus as
claimed in claim 7, wherein said first modulated signal inputted to
said receiving circuit is transmitted from a remote controller in a
room different from one in which said transmitting circuit is
installed.
10. A modulated signal receiving and transmitting apparatus as
claimed in claim 7, wherein said first modulated signal inputted to
said receiving circuit is outputted from a transmitter through a
wire, and said second signal modulated signal outputted from said
transmitting circuit is transmitted through a wire.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a modulated signal transmitting
apparatus for receiving modulated signals and sending them out.
A common process of performing remote control on equipment or
devices to be controlled involves the following operations. A
remote control transmitter modulates a carrier with a command
signal and converts the modulated signal by a light-electricity
conversion means into an infrared signal, which is transmitted as
an infrared remote control signal. The equipment to be controlled
receives the infrared remote control signal at the light receiving
section, converts it into an electric signal, and demodulates it to
recover the command signal. According to the command signal thus
recovered, the controlled equipment performs the required
control.
When such a remote control system is exposed to intermittent
external noise such as from fluorescent lamps, especially when the
carrier frequency of the remote control signal is in the same range
as the external noise frequency, the remote control signal is
interfered with by the noise, with the result that the remote
control signal cannot be correctly received by the controlled
equipment. The command signal therefore cannot be demodulated and
recovered, resulting in an undesired operation of the equipment or
failure to operate.
With a view to overcoming the above drawback experienced with
conventional transmitters, it is an object of this invention to
provide a modulated signal transmitting apparatus which is capable
of outputting modulated remote control signals without being
affected by external noise.
SUMMARY OF THE INVENTION
A modulated signal transmitting apparatus according to this
invention comprises: a control signal output means for receiving a
modulated signal which is generated by modulating a carrier signal
with a certain command signal, the control signal output means
being adapted to output a control signal which corresponds to the
frequency of the carrier signal of the modulated signal; and a
modulated signal output means for receiving the modulated signal
and the control signal; whereby said modulated signal output means
outputs a modulated signal whose carrier frequency is regulated by
the control signal.
In the above configuration, the modulated input signal is entered
into the control signal output means, which outputs a control
signal that corresponds to the frequency of carrier of the
modulated input signal. The modulated signal output means generates
a modulated output signal whose carrier signal has a frequency
corresponding to the control signal. That is, the modulated signal
output by the modulated signal output means is formed as a signal
whose carrier frequency is related to the frequency of the carrier
of the modulated input signal. This makes it possible to produce a
modulated output signal with a carrier whose frequency is not
interfered with by external noise frequency so that the modulated
output signal has immunity to noise.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 are block diagrams showing modulated signal
transmitting apparatuses as embodiments of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the invention will be described by
referring to the attached drawings.
This embodiment shows an infrared remote control system to control
a stereo set in a room A, as a controlled equipment, from another
room B. In the room A are installed a remote control signal
emitting section and the stereo set comprising an amplifier, a
compact disc player, a tuner, speakers and a remote control signal
receiving section. In the room B is installed a remote control
transmitter as well as speakers and another remote control signal
receiving section, which is connected with the remote control
signal emitting section in the room A through a control line.
In the above configuration, in order to listen to music in the room
B by the stereo set placed in the room A, an infrared command
signal should first be transmitted to the remote control signal
receiving section in the room B. The remote control signal
receiving section converts the infrared command signal to an
electric signal to transmit the electric signal to the remote
control signal emitting section in the room A through the control
line. At the remote control signal emitting section, the electrical
signal is converted to another infrared command signal, which is
transmitted to the remote control signal receiving section on the
stereo set. Accordingly, command signals corresponding to the
remote control transmitter is output to the speakers in the room B
through a signal line from the stereo set. But, the infrared
command signal is occasionally interfered with by external noise
such as from fluorescent lamps.
FIGS. 1 and 2 are block diagrams illustrating the embodiments of
the modulated signal transmitting apparatus according to this
invention.
In FIG. 1, reference numeral 1 represents a receiving circuit that
receives infrared remote control signals such as from a remote
control transmitter and which converts the infrared remote control
signal into an electrical signal and outputs a modulated signal of
the remote control signal. 2 stands for a control signal output
circuit for inputting the modulated signal and outputting a
corresponding control signal. Designated 3 is a modulated signal
output circuit which, according to the control signal from the
control signal output circuit 2, changes the carrier frequency of
the modulated signal and then produces a new modulated signal with
the altered carrier frequency. Designated 4 is a transmitting
circuit that converts the modulated signal transferred from the
modulated signal output circuit 3 into an infrared signal and
transmits it as the infrared remote control signal.
The control signal output circuit 2 consists of a filter 21 that
passes only the carrier of the modulated signal from the receiving
circuit 1; and a frequency-voltage conversion circuit (F/V
conversion circuit) 22 for outputting a DC voltage corresponding to
the carrier frequency from the filter 21. The DC voltage thus
produced is output as a control signal from the control signal
output circuit 2. The modulated signal output circuit 3 has a
voltage-controlled filter (VC filter) 31 whose pass band
characteristic is changed according to the DC voltage and which
works as a tuning type filter. The infrared remote control signal
and the modulated signal are signals whose carriers are modulated
by command signals.
In the above configuration, the infrared remote control signal is
entered into the receiving circuit 1 where it is converted into an
electric signal, which is further processed to produce at the
output of the receiving circuit 1 a modulated signal that
corresponds to the received remote control signal. The filter 21
passes only the carrier component of the remote control signal and
transfers it to the F/V conversion circuit 22. The F/V conversion
circuit 22 in turn produces a DC voltage corresponding to the
carrier frequency that has passed through the filter 21.
The modulated signal from the receiving circuit 1 is also supplied
to the VC filter 31, whose pass band characteristic is changed
according to the DC voltage from the F/V conversion circuit 22. The
carrier of the modulated signal contains, in addition to the
fundamental frequency component, even- and odd-numbered orders of
harmonic components. The VC filter 31 therefore passes the command
signal component and has its pass band characteristic altered so
that the fundamental component of the carrier and other harmonic
components can be selectively passed through while preventing those
components that are affected by external noise from passing through
the VC filter. In other words, the VC filter 31 works as a variable
tuning type filter for the carrier of the input modulated
signal.
At the output of the VC filter 31, therefore, a remote control
signal is obtained which has its carrier frequency altered in
accordance with the carrier frequency of the input remote control
signal. The transmitting circuit 4 converts the modulated signal
from the VC filter 31 into an infrared remote control signal and
sends it to the controlled equipment.
FIG. 2 shows another embodiment of the invention. In the figure, a
modulated signal output circuit 3 includes a demodulating circuit
for demodulating the modulated signal from the receiving circuit 1
and outputting the command signal; a voltage-controlled oscillation
(VCO) circuit 33 whose oscillation frequency is changed by the DC
voltage from the F/V conversion circuit 22; and a modulating
circuit 34. In other respects, the second embodiment is similar to
the first embodiment.
In this configuration, the modulated signal from the receiving
circuit 1 is supplied to the demodulating circuit 32, which
demodulates it and outputs the command signal. The VCO circuit 33
produces an oscillation signal whose frequency is controlled by the
DC voltage fed from the F/V conversion circuit 22. The modulating
circuit 34 uses the oscillation signal from the VCO circuit 33 as a
carrier signal and modulates it with the command signal from the
demodulating circuit 32. Since the DC voltage of the F/V conversion
circuit 22 represents the carrier frequency of the command signal
entered into the receiving circuit 1, the oscillated frequency of
the VCO circuit 33 varies with the carrier frequency. Thus, at the
output of the modulating circuit 34 is produced a modulated signal
whose carrier frequency changes with the frequency of the carrier
signal of the remote control signal.
In the preceding embodiments, even when the infrared remote control
signal applied to the receiving circuit 1 is exposed to
intermittently occurring external noise such as from fluorescent
lamps, the infrared remote control signal output from the
transmitting circuit 4 can be normally received by the controlled
equipment where the command signal is correctly demodulated. This
is because the carrier signal of the infrared remote control signal
output from the transmitting circuit 4 has a frequency which is not
easily affected nor interfered with at all by the frequency of such
external noise.
Although the above embodiments have been shown as apparatuses for
transmitting the infrared remote control signal as the modulated
signal, it is also possible to apply this invention to other forms
of modulated signal which may be transmitted by wire or radio.
In summary, even when subjected to external noise, the modulated
signal transmitting apparatus of the invention is able to transmit
the modulated signals in stable condition without being interfered
with by noise.
* * * * *